1. Field of the Invention
The present invention relates generally to an article stock closet, and more particularly to an improvement in a rotatable stock closet including a plurality of open containers for the storage of articles such as electronic parts or similar articles, movable arranged in a plurality of container conveying units arranged vertically one on another.
2. Description of the Prior Art
After extended use of a stock closet of the type described above, the joints or connected point of an endless pull or traction chain inevitably become longer. This may interfere with smooth operation of the chain along guide tracks or rails, and may eventually cause such trouble that the containers run off their tracks.
To solve this problem, two shafts for chain driving sprockets are ordinarily provided. The distance between the axes of the shafts is outwardly adjustable to the extent necessary to absorb slack due to wear of the chain. At the same time, the guide rails have split parts near one or both ends of the straight sections of the rails. The ends of the straight sections adjoin curved sections of the rails so that the split parts may slide away from the ends of the straight sections of the rails to extend the total length of the straight sections by an amount equal to the axial adjustment of the sprocket shaft. This compensates for the slack in the driving chain. Gaps formed between the extended split parts and the ends of the straight sections may be filled with filler plates to form a smooth, continuous connection of the rails. For this purpose, a variety of filler plates having many different sizes are required, to fill the gaps formed by the axial adjustment of the sprocket shafts. Thus, the adjustment is a troublesome job requiring substantial time and labor.
In this device, motors drive the traction chains for the vertically arranged container conveying units. Turning these motors on generally causes very large tension forces on endless driving chains which run between sprockets connecting to the motors and the traction chains. The frame of the rotatable stock closet is thus distorted by the tension forces, especially if many articles are stored in the stock closet. Therefore, the frame must be manufactured strongly enough to prevent such distortion of the frame.
Furthermore, the stock closet is usually large, requiring extensive space for its manufacture. It would be preferable to vary the size of the stock closet depending on the purpose of its use.